This report analyzes the manifestations and treatment of 90 episodes of congestive heart failure in 40 children and adolescents with rheumatic heart disease. By use of specific clinical criteria, 34 episodes could be designated as part of "active" rheumatic inflammation, and 56 as "inactive." The most common signs in "active" and "inactive" groups were hepatic enlargement or tenderness, tachycardia, distention of neck veins, peripheral edema, and weight gain. The most common symptom was dyspnea, but it often was absent and, when present, was usually unaccompanied by rales. Three symptoms uncommon in the congestive failure of adults were frequently noted: cough, nausea, and a right upper quadrant abdominal ache. The latter finding was due to hepatic tenderness, demonstrated by a positive "liver slap" test, that often preceded palpable hepatomegaly and was sometimes the first evidence of decompensation. The "active" and "inactive" distinctions were therapeutically useful in that "active" episodes sometimes responded well to anti-inflammatory agents alone. Digitalis seemed to have equal occurrences of effectiveness or toxicity in "active" or "inactive" patients, and showed no major advantages over diuretics except when ventricular rates were rapid. In "active" patients, anti-inflammatory therapy seemed preferable and most beneficial only in the early untreated stages of the rheumatic attack. Although usually less effective than steroids for this purpose, salicylates were occasionally successful. Decompensation occurring as part of post-therapeutic rebounds in "active" patients could often be managed by digitalis or diuretics, without need for resumption of anti-inflammatory agents and their attendant risk of another post-therapeutic rebound. Except in the specific "active" and "inactive" instances cited above, we believe diuretics are a preferable first choice in the pharmaceutical treatment of the decompensated young rheumatic heart. Success with diuretics obviates not only the hazards of digitalis toxicity, but also the risk of inflammatory recrudescence after steroids.